(Historic) Eruptive Action at Puʻu Huluhulu

Last week some friends from work and I went for a hike up on Mauna Kea near the Visitor Information Station. On our way down we stopped at Puʻu Huluhulu (which I've written about before) for a short hike since one of my friends hadn't been there before.

I wasn't originally planning to take any pictures, but as we were rounding the western end I was struck by something I hadn't noticed before. Move your mouse over the picture below to see it highlighted! (Which effect, incidentally, is a new trick I worked out just for this post. Mobile users, I'm not sure how mouseover effects are emulated, I'm afraid…try long-pressing on the image, perhaps?)

Western end of Puʻu Huluhulu, just off Saddle Road.

What I noticed, which can be seen better in the close up images below, is that at both sides on this end of the hill are pieces of flat rock sticking upwards at an angle. Given how they flank an eruptive cinder cone, I'm drawn to the conclusion that these are pieces of the overlying lava flow through which Puʻu Huluhulu erupted. (I keep wanting to call them the “crust” since they're both pretty thin—a few inches thick at most, especially the one on the right.) Presumably the rock connecting them was pulverized or ejected in the eruption of Puʻu Huluhulu and these pieces were far enough from the center to remain where they ended up.

Close-ups of the two bits of up-thrust crust.

Two miscellaneous comments on the first photo:

1. That sky is surprisingly blue. We actually came down from Mauna Kea a little early because the weather was threatening rain, and there were a lot of patchy clouds and patches of fog on the way down. The wind was blowing pretty hard, and there were a lot of tiny water droplets in the air, so it surprises me there's that much blue sky to be seen.
2. That picture also happens to be a (cropped) panorama I took with my phone. As someone who's put together a fair few panoramas by hand I remember being a bit disappointed in my previous attempts to use the auto-panorama feature in my camera software. I only took this one as something of an experiment, but perhaps the camera software was updated when my phone upgraded to Android 5.1 or something, because I'm actually pretty impressed with the result (I even have a slightly-differently cropped version as my desktop background right now). I'm looking forward to using this more in the future; as should be apparent from this blog I love panoramas, but putting them together is a bit time-consuming so hopefully this'll allow me to take more of them in the future.

Anyway, I thought this was kind of interesting as I didn't notice those bits of crust the last time I was there. A hui hou!